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212 lines
9.5 KiB
PHP
212 lines
9.5 KiB
PHP
<?php
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/*
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Enable support for HTTP/1.x conditional requests in PHP.
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Goal: Optimisation
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- If the client sends a HEAD request, avoid transferring data and return the correct headers.
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- If the client already has the same version in its cache, avoid transferring data again (304 Not Modified).
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- Possibility to control cache for client and proxies (public or private policy, life time).
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- When $feedMode is set to true, in the case of a RSS/ATOM feed,
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it puts a timestamp in the global variable $clientCacheDate to allow the sending of only the articles newer than the client's cache.
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- When $compression is set to true, compress the data before sending it to the client and persitent connections are allowed.
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- When $session is set to true, automatically checks if $_SESSION has been modified during the last generation the document.
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Interface:
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- function httpConditional($UnixTimeStamp,$cacheSeconds=0,$cachePrivacy=0,$feedMode=false,$compression=false)
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[Required] $UnixTimeStamp: Date of the last modification of the data to send to the client (Unix Timestamp format).
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[Implied] $cacheSeconds=0: Lifetime in seconds of the document. If $cacheSeconds<0, cache is disabled. If $cacheSeconds==0, the document will be revalidated each time it is accessed. If $cacheSeconds>0, the document will be cashed and not revalidated against the server for this delay.
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[Implied] $cachePrivacy=0: 0=private, 1=normal (public), 2=forced public. When public, it allows a cashed document ($cacheSeconds>0) to be shared by several users.
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[Implied] $feedMode=false: Special RSS/ATOM feeds. When true, it sets $cachePrivacy to 0 (private), does not use the modification time of the script itself, and puts the date of the client's cache (or a old date from 1980) in the global variable $clientCacheDate.
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[implied] $compression=false: Enable the compression and allows persistant connections (automatic detection of the capacities of the client).
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[implied] $session=false: To be turned on when sessions are used. Checks if the data contained in $_SESSION has been modified during the last generation the document.
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Returns: True if the connection can be closed (e.g.: the client has already the lastest version), false if the new content has to be send to the client.
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Typical use:
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<?php
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require_once('http-conditional.php');
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//Date of the last modification of the content (Unix Timestamp format).
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//Examples: query the database, or last modification of a static file.
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$dateLastModification=...;
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if (httpConditional($dateLastModification))
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{
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... //Close database connections, and other cleaning.
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exit(); //No need to send anything
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}
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//Do not send any text to the client before this line.
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... //Rest of the script, just as you would do normally.
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?>
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Version 1.7 beta, 2013-12-02, http://alexandre.alapetite.fr/doc-alex/php-http-304/
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------------------------------------------------------------------
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Written by Alexandre Alapetite, http://alexandre.alapetite.fr/cv/
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Copyright 2004-2013, Licence: Creative Commons "Attribution-ShareAlike 2.0 France" BY-SA (FR),
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http://creativecommons.org/licenses/by-sa/2.0/fr/
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http://alexandre.alapetite.fr/divers/apropos/#by-sa
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- Attribution. You must give the original author credit
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- Share Alike. If you alter, transform, or build upon this work,
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you may distribute the resulting work only under a license identical to this one
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(Can be included in GPL/LGPL projects)
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- The French law is authoritative
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- Any of these conditions can be waived if you get permission from Alexandre Alapetite
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- Please send to Alexandre Alapetite the modifications you make,
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in order to improve this file for the benefit of everybody
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If you want to distribute this code, please do it as a link to:
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http://alexandre.alapetite.fr/doc-alex/php-http-304/
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*/
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//In RSS/ATOM feedMode, contains the date of the clients last update.
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$clientCacheDate=0; //Global public variable because PHP4 does not allow conditional arguments by reference
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$_sessionMode=false; //Global private variable
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function httpConditional($UnixTimeStamp,$cacheSeconds=0,$cachePrivacy=0,$feedMode=false,$compression=false,$session=false)
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{//Credits: http://alexandre.alapetite.fr/doc-alex/php-http-304/
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//RFC2616 HTTP/1.1: http://www.w3.org/Protocols/rfc2616/rfc2616.html
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//RFC1945 HTTP/1.0: http://www.w3.org/Protocols/rfc1945/rfc1945.txt
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if (headers_sent()) return false;
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if (isset($_SERVER['SCRIPT_FILENAME'])) $scriptName=$_SERVER['SCRIPT_FILENAME'];
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elseif (isset($_SERVER['PATH_TRANSLATED'])) $scriptName=$_SERVER['PATH_TRANSLATED'];
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else return false;
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if ((!$feedMode)&&(($modifScript=filemtime($scriptName))>$UnixTimeStamp))
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$UnixTimeStamp=$modifScript;
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$UnixTimeStamp=min($UnixTimeStamp,time());
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$is304=true;
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$is412=false;
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$nbCond=0;
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//rfc2616-sec3.html#sec3.3.1
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$dateLastModif=gmdate('D, d M Y H:i:s \G\M\T',$UnixTimeStamp);
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$dateCacheClient='Thu, 10 Jan 1980 20:30:40 GMT';
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//rfc2616-sec14.html#sec14.19 //='"0123456789abcdef0123456789abcdef"'
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if (isset($_SERVER['QUERY_STRING'])) $myQuery='?'.$_SERVER['QUERY_STRING'];
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else $myQuery='';
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if ($session&&isset($_SESSION))
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{
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global $_sessionMode;
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$_sessionMode=$session;
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$myQuery.=print_r($_SESSION,true).session_name().'='.session_id();
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}
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$etagServer='"'.md5($scriptName.$myQuery.'#'.$dateLastModif).'"';
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if ((!$is412)&&isset($_SERVER['HTTP_IF_MATCH']))
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{//rfc2616-sec14.html#sec14.24
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$etagsClient=stripslashes($_SERVER['HTTP_IF_MATCH']);
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$is412=(($etagClient!=='*')&&(strpos($etagsClient,$etagServer)===false));
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}
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if ($is304&&isset($_SERVER['HTTP_IF_MODIFIED_SINCE']))
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{//rfc2616-sec14.html#sec14.25 //rfc1945.txt
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$nbCond++;
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$dateCacheClient=$_SERVER['HTTP_IF_MODIFIED_SINCE'];
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$p=strpos($dateCacheClient,';');
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if ($p!==false)
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$dateCacheClient=substr($dateCacheClient,0,$p);
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$is304=($dateCacheClient==$dateLastModif);
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}
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if ($is304&&isset($_SERVER['HTTP_IF_NONE_MATCH']))
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{//rfc2616-sec14.html#sec14.26
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$nbCond++;
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$etagClient=stripslashes($_SERVER['HTTP_IF_NONE_MATCH']);
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$is304=(($etagClient===$etagServer)||($etagClient==='*'));
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}
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if ((!$is412)&&isset($_SERVER['HTTP_IF_UNMODIFIED_SINCE']))
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{//rfc2616-sec14.html#sec14.28
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$dateCacheClient=$_SERVER['HTTP_IF_UNMODIFIED_SINCE'];
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$p=strpos($dateCacheClient,';');
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if ($p!==false)
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$dateCacheClient=substr($dateCacheClient,0,$p);
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$is412=($dateCacheClient!==$dateLastModif);
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}
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if ($feedMode)
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{//Special RSS/ATOM
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global $clientCacheDate;
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$clientCacheDate=@strtotime($dateCacheClient);
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$cachePrivacy=0;
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}
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if ($is412)
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{//rfc2616-sec10.html#sec10.4.13
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header('HTTP/1.1 412 Precondition Failed');
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header('Cache-Control: private, max-age=0, must-revalidate');
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header('Content-Type: text/plain');
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echo "HTTP/1.1 Error 412 Precondition Failed: Precondition request failed positive evaluation\n";
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return true;
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}
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elseif ($is304&&($nbCond>0))
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{//rfc2616-sec10.html#sec10.3.5
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header('HTTP/1.0 304 Not Modified');
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header('Etag: '.$etagServer);
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if ($feedMode) header('Connection: close'); //Comment this line under IIS
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return true;
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}
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else
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{//rfc2616-sec10.html#sec10.2.1
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//rfc2616-sec14.html#sec14.3
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if ($compression) ob_start('_httpConditionalCallBack'); //Will check HTTP_ACCEPT_ENCODING
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//header('HTTP/1.0 200 OK');
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if ($cacheSeconds<0)
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{
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$cache='private, no-cache, no-store, must-revalidate';
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//header('Expires: 0');
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header('Pragma: no-cache');
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}
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else
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{
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if ($cacheSeconds===0)
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{
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$cache='private, must-revalidate, ';
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//header('Expires: 0');
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}
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elseif ($cachePrivacy===0) $cache='private, ';
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elseif ($cachePrivacy===2) $cache='public, ';
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else $cache='';
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$cache.='max-age='.floor($cacheSeconds);
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}
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//header('Expires: '.gmdate('D, d M Y H:i:s \G\M\T',time()+$cacheSeconds)); //HTTP/1.0 //rfc2616-sec14.html#sec14.21
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header('Cache-Control: '.$cache); //rfc2616-sec14.html#sec14.9
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header('Last-Modified: '.$dateLastModif);
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header('Etag: '.$etagServer);
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if ($feedMode) header('Connection: close'); //rfc2616-sec14.html#sec14.10 //Comment this line under IIS
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return $_SERVER['REQUEST_METHOD']==='HEAD'; //rfc2616-sec9.html#sec9.4
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}
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}
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function _httpConditionalCallBack($buffer,$mode=5)
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{//Private function automatically called at the end of the script when compression is enabled
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//rfc2616-sec14.html#sec14.11
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//You can adjust the level of compression with zlib.output_compression_level in php.ini
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if (extension_loaded('zlib')&&(!ini_get('zlib.output_compression')))
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{
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$buffer2=ob_gzhandler($buffer,$mode); //Will check HTTP_ACCEPT_ENCODING and put correct headers such as Vary //rfc2616-sec14.html#sec14.44
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if (strlen($buffer2)>1) //When ob_gzhandler succeeded
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$buffer=$buffer2;
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}
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header('Content-Length: '.strlen($buffer)); //Allows persistant connections //rfc2616-sec14.html#sec14.13
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return $buffer;
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}
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function httpConditionalRefresh($UnixTimeStamp)
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{//Update HTTP headers if the content has just been modified by the client's request
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//See an example on http://alexandre.alapetite.fr/doc-alex/compteur/
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if (headers_sent()) return false;
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if (isset($_SERVER['SCRIPT_FILENAME'])) $scriptName=$_SERVER['SCRIPT_FILENAME'];
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elseif (isset($_SERVER['PATH_TRANSLATED'])) $scriptName=$_SERVER['PATH_TRANSLATED'];
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else return false;
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$dateLastModif=gmdate('D, d M Y H:i:s \G\M\T',$UnixTimeStamp);
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if (isset($_SERVER['QUERY_STRING'])) $myQuery='?'.$_SERVER['QUERY_STRING'];
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else $myQuery='';
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global $_sessionMode;
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if ($_sessionMode&&isset($_SESSION))
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$myQuery.=print_r($_SESSION,true).session_name().'='.session_id();
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$etagServer='"'.md5($scriptName.$myQuery.'#'.$dateLastModif).'"';
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header('Last-Modified: '.$dateLastModif);
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header('Etag: '.$etagServer);
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}
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